Henrique von Gersdorff, Ph.D.

Senior Scientist, Vollum Institute

Background

Henrique von Gersdorff earned a Ph.D. in Physics from the University of Minnesota and a Ph.D. in Neurobiology from Stony Brook University in New York. He received his B.S. in Physics from the Federal University of Rio de Janeiro, Brazil. He was a research scientist in high-energy physics at Brookhaven National Laboratory, and had postdoctoral fellowships at Stony Brook University and the Max-Planck Institute for Biophysical Chemistry, Department of Membrane Biophysics, Göttingen. In 1998 he was appointed assistant scientist in the Vollum Institute and was promoted to scientist in 2004 and senior scientist in 2009. von Gersdorff also holds a faculty appointment in the Department of Physiology and Pharmacology in the School of Medicine at OHSU.

Summary of Current Research

Sensory information is conveyed by neurons and synapses specialized to faithfully transmit large amounts of information at high rates. A key event in synaptic transmission is the release of neurotransmitter via vesicle fusion at synaptic terminals. Direct studies of synaptic terminals have been hampered by their small sizes and technical constraints. However, using high time resolution patch-clamp membrane capacitance measurements, von Gersdorff and his associates have studied the kinetics of vesicle fusion (exocytosis) and subsequent membrane retrieval (endocytosis) in single, live synaptic terminals from bipolar cells of the goldfish retina and from hair cells of the frog amphibian papilla. These cells have compact ribbon-type active zones that contain a large pool of releasable vesicles suitable for the transfer of high bandwidths of information. Following short depolarizations, a fast form of endocytosis can be observed, indicating that synaptic vesicle membrane is quickly re-internalized after vesicle fusion. Von Gersdorff and his colleagues are presently investigating mechanisms for short-term synaptic plasticity at ribbon synapses in mouse retinal slices and also multivesicular release at the hair cell synapses using capacitance measurements together with paired recordings of hair cells and their afferent fibers. The lab is also using imaging techniques to record optically the fast dynamics of calcium changes in active zones and nerve fibers.

To study conventional active zone synapses, the lab has been examining the calyx of Held nerve terminal, a pivotal element in the auditory brainstem circuitry that computes sound source localization. Precise timing of action potential discharges is essential for accomplishing this task. Nevertheless, the mechanisms that modulate and preserve the timing of spikes are poorly understood. Von Gersdorff and his coworkers are studying these mechanisms and short-term forms of plasticity at this synapse. The large size of the calyx terminal allows them to directly patch-clamp the terminal and the postsynaptic cell simultaneously, and thus to measure calcium currents, presynaptic capacitance changes, and glutamate release. This direct access to the terminal allows the lab to study the kinetics of synaptic vesicle exocytosis and endocytosis, neurotransmitter reuptake mechanisms, and the modulation of postsynaptic spikes. Presently, the lab is focused on revealing the developmental changes that fine-tune auditory synapses for short synaptic delays and for sustained high frequency firing.